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Purdue Entomology Professor Ralph Williams and Jake Rowland (B.S. ‘08) Say Mosquito Activity So Far, So Good This Year

by Dorothy Schneider
Journal &amp; Courier

The itching and scratching levels aren't too high yet this year in Tippecanoe County.

Officials out monitoring mosquito activity in the area have not found excessive larvae colonies in the usual places.

"Even though it's been a wet start to the year, there hasn't been that much activity," said Jacob Rowland, an environmentalist with the Tippecanoe County's health department.

That might change by the end of the week. The moisture left behind from Monday's rain is combining with hot weather this week to produce ideal mosquito breeding conditions.

"Those topical, rainwater mosquitoes may emerge in a few days," said Ralph Williams, a professor of entomology at Purdue University. "As long as we have intermittent rains like this, we possibly will see the nuisance biting activity level rise."

Williams said there's no way to issue a long-term forecast for mosquito activity this summer, because the mosquito population is totally dependent on changing weather conditions.

Mosquitoes lay eggs on the surface of standing water. The whole hatching and maturation process of a mosquito can be completed in five to 10 days.

Rain is a double-edged sword in the mosquito breeding process, Williams said. Nuisance biting mosquitoes emerge from standing water left behind by a storm. But a heavy downpour can flush out the larvae of another type of mosquito -- the type more likely to be carrying human-transmittable diseases.

"If we start getting into a drought period, then you're more concerned about the stagnant water and breeding of those (mosquitoes) more likely to carry West Nile and encephalitis viruses," Williams said.

The Indiana Department of Health monitors West Nile activity throughout the state during the summer months and will alert local departments if mosquitoes from the area test positive.

"They haven't seen that as an issue as of now," Williams said.

The types of mosquitoes starting to become active now do present a threat to pets. Williams said the mosquitoes coming out can carry dog heartworm, so pet owners need to guard against it through medication and by keeping animals indoors during peak mosquito activities times in the dawn and dusk hours.

"Pet owners should seek the advice of their veterinarian," he said.

Rowland was out patrolling areas Tuesday where mosquitoes often breed, ranging from swampy ditches alongside county roads to muddy puddles at the Tippecanoe County 4-H Fairgrounds. But in most places, so far, Rowland came up empty.

If he finds larvae in water pools around the county, Rowland will usually treat it with a spray that kills it. In some cases, he'll first bring some of the larvae back to the department for testing.